Assumptions
- The export is value-based. Formulas become results; formatting, charts and macros are dropped.
- The EUC-KR table is built by reversing the browser’s own EUC-KR decoder. Characters missing from it become ? and are listed before you download.
- Everything runs in memory, up to 25 MB. Very large workbooks depend on how much memory your browser allows.
How it is calculated
- The workbook is parsed in your browser and each sheet is listed with its row and column count.
- Cells of the selected sheets are rendered as text: dates in the format you chose, numbers without scientific notation.
- Values containing the delimiter, quotes or line breaks are escaped per RFC 4180 and joined into rows.
- The text is encoded in your chosen encoding and downloaded. Selecting several sheets produces one ZIP.
Examples
Common mistakes
- Watch leading zeros and long numbers. ZIP codes and account numbers already stored as numbers in Excel have lost their leading zeros before the export begins. Format them as text in the source file.
- Match the delimiter to the recipient. Semicolons for European Excel, commas elsewhere, tabs when pasting into a spreadsheet.
- EUC-KR covers Korean and basic Han characters only. Emoji and unusual symbols need UTF-8.
FAQ
Why not just use Save As → CSV in Excel?
You can. But Excel writes CSV in your system code page rather than UTF-8, so the file often breaks when another program or server reads it. It also saves only the active sheet, and dates come out in whatever display format the cells happened to use. Here you choose the encoding, delimiter and date format, and export several sheets at once.
What is a UTF-8 BOM and do I want one?
The byte order mark is a three-byte prefix (EF BB BF) that tells Excel the file is UTF-8. Without it, Excel falls back to the system code page and non-Latin text appears as mojibake, so pick UTF-8 with BOM for files people will open in Excel. For files going into a script, a database import or a Git repository, choose plain UTF-8, because the BOM ends up glued to the first column name.
When should I pick semicolons?
Excel installations in countries that use the comma as the decimal separator, such as Germany, France, Spain and Brazil, expect semicolon-separated files. If your recipient opens a comma CSV and sees every row crammed into one column, semicolons are what they need. Tab-separated output is the safest choice for pasting straight into a spreadsheet.
How are commas inside a cell handled?
By RFC 4180. If a value contains the delimiter, a double quote or a line break, the whole value is wrapped in double quotes and inner quotes are doubled. Switching the delimiter to tab or semicolon means commas no longer need quoting and are written as-is.
What is lost in the conversion?
CSV holds values only. Formulas become their calculated results; colours, fonts, column widths, charts, images and macros disappear. In a merged range only the top-left cell keeps the value. If you need any of that, keep the .xlsx.
Is my file uploaded anywhere?
No. Reading the workbook and writing the CSV both happen in your browser. Neither the contents nor the file name leaves your device.